Selective reclosing time mechanism for repeating circuit interrupters



' Sept. 16, 1958 E. J. STRAMOWSKI 2,352,638

SELECTIVE RECLOSING TIME MECHANISM FOR REPEATING CIRCUIT INTERRUPTERS 4Sheets-Sheet 1 Filed Aug. 1'7, 1956 INVENTOR. fdmund J." 5tram0ws/(ziwmzw vi ttbrnqy P 16, 1953 E. J. STRAMOWSKI 2,352,638

SELECTIVE RECLOSING TIME MECHANISM FOR REPEATING 4 CIRCUIT INTERRUFTERSFiled Aug. 17, 1956 4 Sheets-Sheet 2 INVENTOR. farm/27a J Stramawsklial/.4. W

afttorne w Sept. 16, 1958 E. SELECTIVE RECLOSIN Filed Aug. 17, 1956 J.STRAMOWSK] G TIME MECHANISM FOR REPEATING Ill CIRCUIT INTERRUPTERS 4Sheets-Sneet 3 INVENTOR. farm/27d J Stra mews/f4 kfflw afttormy Sept.16, 1958 v 2,852,638 SELECTIVE RECLOSING TIME MECHANISM FOR REPEATINGCIRCUIT INTERRUPTERS 7 Filed Aug. 17, 1956 E. J. STRAMOWSKI 4Sheets-Sheet 4 III INVENTOR. fdmupa J Stramowskl fly! W afttarny2,52,638 Patented Sept. 16, 1958 SELEQTKVE REQLOSENG Til'viE MECHANISMF013 REPEATING CIRCUIT HNTERRUPTERS Edmund J. Stramowshi, Mil-. vaulree,Win, to McGraw-Edrson Company, a corporation of Deiaware ApplicationAugust 17, 1956, Serial No. 604,668

s tClairns. (Cl. wit-39) This invention relates to improvements incircuit interrupters, and in particular, to that type of interrupterknown as a repeating circuit recloser.

A typical, but not exclusive, form of circuit interrupter to which thepresent invention may be applied is illustrated in the copendingapplication of A. Van Ryan et al., Ser. No. 379,046, filed September 8,1953, now Patent No. 2,804,521, issued August 27, 1957, and assigned tothe assignee of the instant invention.

The cited patent application illustrates in great detail a polyphasecircuit interrupter adapted to execute a plurality of quickly successivefast opening operations followed by a series of slow or retarded openingoperations. The length of time required for reclosing the circuitinterrupter after each opening is substantially constant for alloperations and is relegated largely to chance and to inherent designcharacteristics which impede closing through friction and uncontrolledthrottling of hydraulic fluid.

In applying such circuit interrupters to distribution circuits, it isassumed that most faults on the system will be temporary and clearedduring the initial fast opening operation. A. certain number of faults,however, are more durable and require a longer burning time beforeclearing, thus accounting for the delayed opening operations. If theinterrupter executes its full sequence of fast and retarded Operations,indicating that the fault is permanent, the interrupter locks out andpermanently de-energizes the line until the fault is repaired and theinterrupter is manually reset.

The normal sequence of operations, however, is not acceptable for allinstallations because it is preferable on many occasions to reclose theinterrupter very quickly after it has opened in response to flow offault current. A need for rapid reclosing is exemplified where there arealternating current motors connected to the system whose line contactorsdrop out and de-energize the motors for every temporary fault occurringon the lines. Usually, circuit interrupters of the type here underdiscussion are designed to reclose in approximately two seconds or 120cycles, a period greatly in excess of that tolerable where dropping ofthe line contactors is to be avoided.

The problem of having motors stop for every temporary fault such as asingle stroke of lightning or the swinging together of adjacent phasewires in a wind storm is particularly annoying in areas wherealternating current motors are adapted to drive irrigation pumps whichsup ply a reservoir out of which a syphon system operates to distributethe water to various channels in the field being irrigated. Under thecircumstances, the loss of pump pressure not only drops the water levelin the reservoir but breaks the vacuum in a multitude of syphons andnecessitates restarting all syphons by manual means before irrigationmay be resumed.

Consequently, it is a general object of the present invention toovercome the above cited difficulties by providing an improved circuitinterrupter which is more versatile in the respect that timing on bothits opening and closing sequence is more fully controllable by manualdiscretion. I

A further object of this invention is to provide an automatic reclosingcircuit interrupter with mechanism which permits preselection of thenumber of fast interrupter reclosures and which further automaticallyconverts to time controlled retarded or delayed reclosing after adefinite number of operations, the mechanism be ing so designed that itdoes not interfere with the normal sequence of fast and retarded openingoperations of the interrupter.

Other more specific objects will appear periodically throughout thecourse of the ensuing specification.

In general terms, the invention is characterized by a fluid immersedcircuit interrupter having a set of interrupting contacts and powermeans for opening and closing the contacts instantaneously uponoccurrence of an overload. The closing means constitute a magnet coiladapted to attract a central plunger to one position for reclosing theinterrupter and to release the plunger to another position upon openingof the interrupter and simultaneously closing an auxiliary switch forre-energizing the magnet coil and repeating the closing operation. Theinvention contemplates very rapid movement of the plunger in closing theauxiliary switch on the first of a series of operations and laterbringing mechanism into effect which retards the plunger andconsequently increases the time between opening of the interrupter andreclosing the auxiliary switch for energizing the solenoid coil again.

The exemplary interrupter also includes a hydraulic pump which takes astroke in accordance with each switch opening and closing operation anddelivers .a measured quantity of hydraulic fluid to an integratingcumulative piston which advances axially step-by-step in accordance withstrokes of the pump. Lockout mechanism is arranged to be actuated byadvancement of the integrating piston to an ultimate position, whereuponthe lockout means permanently depresses the auxiliary closing solenoidswitch and thereby tie-energizes the reclosing mechanism.

A more detailed description'of a circuit interrupter employing theinvention and also of the novel selective reclosing time mechanismitself, will be made in conjunction with the following drawings inwhich:

Fig. 1 schematically represents the essential elements of one form ofcircuit interrupter embodying the reclosing time control arrangementconstituting the invention, the novel subject matter being shown. inthis view principally in sectional rear elevation and the interrupterelements corresponding with open circuit position;

Fig. 2 shows the same elements as in Fig. 1, but with the interrupterelements con-esponding with closed circuit position;

Fig. 3 is a left side elevational view of the invention with a portionthereof in section and rotated on a vertical axis to avoid an appearanceof foreshortening;

Fig. 4 is a front elevational assembly view of the invention;

Fig. 5 is an enlarged sectional view showingelements of the invention asthey appear when they are ineffective to retard reclosing of the circuitinterrupter; and,

Fig. 6 is similar to Fig. 5, but shows the elements of the inventionwhen they are effective to retard reclosing of the circuit interrupter.

Before proceeding with describing the novel reclosing time controlmechanism in detail, the basic components of a typical circuitinterrupter to which the invention may be applied will be described inconnection with the schematic representation of such components in Figs.1 and 2. It will be understood that all parts now to be described arearranged to be splashed orirnmersed in an insulating fluid ambient, suchas oil, contained within a metal tank, not shown. Attention is invitedto the cited figures where it is seen that the circuit interrupter isprovided with an extensible main contact opening spring 1 anchored atone end and attached at the other to a rigid power bar 2 on which iscarried a plurality of bell cranks 3, 4, and 5. One arm of each bellcrank is attached to an insulating link 6, 7, and 3, respectively, whichextend down and support the main line circuit interrupting switches, notshown. In Fig. 1, opening spring 1 is contracted and all bell cranks 3,4 and 5 are rotated in a clockwise direction for forcing the line switchinsulating links 6, 7, 8 downwardly and opening the line switches. InFig. 2, switch opening spring 1 is extended and the bell cranks arerotated counterclockwise whereupon they lift the insulating links andclose the main line switches.

When power bar 2 is shifted to the left, as in 2, in preparation foropening the line switches under the influence of opening spring 1, thepower bar is held in that positiono by a toggle link mechanismrepresented schematically by a pair of collapsible links 9 and 10, thefirst of which is attached pivotally to the bell crank 3 and the otheris pinned to a rack shaft 15. When opening spring 1 is loaded, the twolinks 9 and 10 are tenuously latched at their center 16 so as to act asa single rigid member extending from shaft to hell crank 3. The togglelink mechanism is shown in considerable detail in the aforementioned VanRyan application, so that, for the sake of brevity, it will not befurther described herein. It is sufiicient to understand, however, thatthe toggle link mechanism, when latched, acts as a rigid member betweenshaft 15 and bell crank 3 and when unlatched collapses to permit quickretraction of power bar 2 to the right under the influence of openingspring 1 to thereby open the line switches quickly. The toggle linkmechanism is collapsed through control by a trip bar 17 which extendslaterally adjacent the hinge latch 16 of the toggle link mechanism. Tripbar 17 is provided with a pin 18 which extends into contact relationwith the latch and causes breaking of the latter when the trip bar isshifted from right to left. The trip bar is preferably spring returned.

The trip bar 17 is operated in response to overload current flowing inthe lines being controlled by the interrupter. Current response isachieved through the agency of a series coil 19 adapted to attract amagnetic plunger 20 downwardly in the coil whenever an overload currentof a predetermined magnitude traverses the latter. Plunger 20 isattached to a bell crank 21 having one arm extending into the path ofanother lateral pin 22 projecting from trip bar 17. It is evident thatcounterclockwise rotation of tripping bell crank 21 will strike drivenpin 22 and cause the trip bar 17 to move and collapse toggle links 9 and10 in the manner described hereinbefore, thereby releasing power bar 2and rotating bell cranks 3, 4, 5 to open the interrupting switches.

Power for resetting the toggle link mechanism and extending openingspring 1 is derived from a large shunt solenoid closing coil 23 suppliedthrough an auxiliary switch generally designated by the referencenumeral 24, both of which are connected in series and across a pair ofmain power lines. When the interrupter is in closed circuit position, itwill be noted in Fig. 2 that a large solenoid plunger 25 has come torest near the bottom of shunt closing coil 23 and that it is latched indownward position through engagement of a pawl 29 by means of a plungerlatch finger 30 carried on power bar 2. The arrangement of thecomponents is preferably such that bell cranks 6, 7 and 8 will berotated from their positions in Fig. 2 to their clockwise positions inFig. l, corresponding with full opening of the line switches, beforelatch finger 30 releases dog 29 to allow retraction of pluger 25upwardly under the influence of a coil spring 31 which normally .biasesthe plunger upwardly.

In Figs. 1 and 2, plunger .25 is shown as loosely fitting 4 in cylinder26 defined by the interior of coil 23. It will be understood that in theactual construction represented in Figs. 3 through 6 that plunger 25 isfairly tight in the cylinder so that no appreciable leakage can occurlongitudinally of the plunger when it reciprocates.

Switch closing force and the force for loading the switch opening springis derived simultaneously from downward reciprocation of plunger 25 andtransmitted to shaft 15 through the medium of a lever 32 fixedly pinnedto the shaft. Thus, by comparing Fig. 1, which shows the switch in openposition and the opening spring contracted, with Fig. 2, which shows theopening spring extended and the switch closed, it will be seen thatrotation of shaft 15 through downward movement of the plunger willrotate bell crank 3 at the far left counter-clockwise through therigidly connected toggle links 9, 1i) and stress the opening spring 1for the next reopening operation. Observe in Fig. 2 that when the mainswitches are closed, plunger 25 is in its lowermost position withinshunt closing coil 23. Further observe in Fig. 1 that immediately afteropening of the line switches, plunger 25 is in its uppermost position atwhich time auxiliary closing switch 24 is in its closed circuit positionfor re-energizing closing solenoid 23 and again attracting the plungerdown, in which position it is normally held by latch finger 30 asdescribed above.

Auxiliary switch 24 is arranged to close the circuit through closingsolenoid 23 only after plunger 25 has reached the uppermost point in itsstroke as in Fig. l. Energization is continued during the downwardstroke of plunger 25 and is discontinued by opening the auxiliary switchas in Fig. 2 when the plunger reaches the bottom of its stroke. It istherefor evident that closing solenoid 23 is normally de-energized aftercompletion of its power stroke.

it is important to note that plunger 25 remains in its lowermostposition until the line switches are fully opened as indicated by theposition of bell cranks 3, 4, 5 in Fig. 1, after which plunger 25 isreleased for upwardnretrao tion and closure of auxiliary switch 24. Itis therefore abundantly clear that the elapsed time between opening ofthe interrupter and closing of the auxiliary switch for the purpose ofreclosing the interrupter is controlled by governing the rate of ascentof plunger 25. Further details regarding the manner in which the ascent.1s controlled will be set forth hereinafter.

Attention is now focused on the mechanism for opening and closingauxiliary switch 24 at the proper tunes, see Figs. 1 and 2. Auxiliaryswitch 24 is operated by an overcenter mechanism comprising a spring 33stretched between a pair of pivotally joined links 34 and 35. Thelongest link 35 carries at its free end a rod 36 which actuates theauxiliary switch, and the other link 34 is slotted at its end 37 forengagement with a crank pin 38 carried rigidly by a crank disc 39afiixed to shaft 15.

When the interrupter is executing its series of opening and reclosingoperations prior to lockout, auxiliary switch 24 is moved between openedand closed positions with a snap action. This is accomplished byintermittently oscillating the slotted end 37 of li k 34 above and belowthe line of action of spring 33. For example, when the interrupter isclosed as in Fig. 2, the auxiliary switch 24 is open and over-centerspring 33 is below the pivot point 40 interconnecting links 34 and 35.When the interrupter is open as in Fig. 1, previous rotation of rockshaft 15 has moved slotted link 34 in a clockwise direction until spring33 has passed over the pivot connection A l of the two links, whereuponauxiliary switch rod 36 is moved upward rapidly. Since spring 33 drivesthe auxiliary switch, it is seen that the latter operates independentlyof the speed of rotation of rock shaft 15.

As implied above, integrating mechanism is also provided for totallingthe number of circuit interrupter opening and reclosing operations andfor actuating a lockout mechanism which permanently holds auxiliaryswitch 24 open to efiect lockout of the interrupter. Referring furtherto Figs. 1 and 2, it will be seen that the interrupter is provided witha hydraulic pump including a cylinder 45 and a reciprocatory piston 46the latter of which is causedto execute a single stroke each time theinterrupter recleses. Means for driving the pump piston 46 by theoperating mechanism of the interrupter may take a number of forms withinthe purview of a skilled artisan so they have been omitted for the sakeof brevity and since they do not constitute an essential forunderstanding the instant invention. A pump driving arrangement may beseen in greater detail in the aforementioned Van Ryan et al.application.

Each stroke of pump piston 46 delivers a measured quantity of oilunderneath an integrating piston 47 which moves upwardly step-by-step ina manner obvious upon inspection of Figs. 1 and 2. As the integratingpiston 47 moves upwardly in steps it drives an L-shaped lever 43 whichis in turn connected to a lookout bar 49. Upward advancement ofintegrating piston 47 causes a corresponding lateral advancement oflockout bar 49 toward a latch arm 56 biased in a clockwise direction bya tension spring 52. Latch arm 56 presses at 52 against an elongatedauxiliary switch control bar 53 in opposition to another strongertension spring 54. Auxiliary switch control bar 53 is supported on ashort pivot lever 55 to which spring 54 is attached and the control baris further guided by a fixed pin 56 residing in an elongated slot 57.When lockout lever 56) is rotated clockwise upon being struck by lockoutbar 49, tension spring 5 retracts switch depressing bar to the right.Upon this event an additional depressing lever 66, pivotally attached tothe switch depressing bar 53, swings on its fixed pivot 61 in aclockwise direction whereupon it presses on auxiliary switch carryinglink 35 and holds the auxiliary switch open permanently. In order torestore electric service through the interrupter after it has beenlocked out in the manner just described, auxiliary switch control bar 53must be shifted and returned to its position in Fig. l and lockout latch56 reset as in that figure by manual means, not shown. This permitsreclosure of auxiliary switch 2 and accordingly reclosure of theinterrupter for repeating its series of opening and closing operationsshould an other fault occur. Also during the lockout period, integratingpiston 67 slowly resettles to its lowermost initial position within itscylinder 44 and prepares itself for another full series of countingoperations.

The selective reclosing time mechanism cons "tuting the invention willnow be described in detail. It was stated above that controlling therate of ascent of the solenoid plunger 25 is the principal factorinvolved in controlling the time lapse between tripping and reclosing ofthe circuit interrupter. For this purpose, the invention features themechanism designated generally by the reference numeral 65, which can beset for a number of fast reclosing operations and which converts slow orretarded reclosing automatically by means of control derived indirectlyfrom the integrating piston 4-7. The rate of plunger ascent is governedby automatically controlling an orifice 66 which places the plungercylinder 26 in communication with the ambient fluid of the circuitinterrupter. In Figs. 1-5, it will be seen that for fast reclosing adisc type of throttle valve 67 is restrained away from orifice 66 sothat when plunger 25 rises it may draw oil freely through orifice 66without any retardation of the plunger. In Fig. 6, however, throttlevalve 67 has been released for move ment to a position where it closesorifice 66 so that when plunger 25 rises its movement is retarded,because fluid can then only be drawn through a small central aperture 68in the throttle valve disc 67. As is evident from the drawings, when thethrottle valve 67 seats to close orifice 66 there is no othersignificant fluid inlet to cylinder 26' aside from the small aperture 68in the throttle valve.

Throttle valve 67 is normally biased toward closing orifice 66 by meansof a soft compression spring 69 interposed between the valve disc and areservoir casting 70. During fast reclosing, throttle disc 67 isrestrained away from orifice 66 by means of a tubular auxiliary piston71 having a long slot 72 in its side, see Figs. 5 and 6, which normallyoverhangs and engages the throttle valve. Piston 71 is in turn held downin a sense by vacuum which would be created by withdrawal of the pistonfrom a normally totally sealed reservoir chamber '73. It will be notedthat slot 72 in auxiliary piston 71 is long enough to permit the fulltravel of throttle valve 67 from its open position in Fig. 5 to itsclosed position represented in Fig. 6 when the auxiliary piston iselevated from reservoir 73. Piston 71 is provided with an interior ballcheck valve 74 whose control direction of oil flow is such that thepiston 71 may be plunged easily into reservoir 73 but the piston resistswithdrawal by virtue of the ball valve 74 seating. A small hole 75underneath the ball 74 places the interior of the reservoir 73 and thefluid ambient in the circular interrupter tank in communication throughthe tubular throttle valve restraining piston 71.

if left unrestrained during the extended period in which the interrupteris normally closed and in which solenoid plunger 25 is in its lowermostposition as in Fig. 5, auxiliary piston 71 may tend to .yield upwardlydue to leakage and permit unwarranted closing of orifice 66 by throttlevalve 67. To avoid this, a light weight tubular depressing rod 77 isdisposed in free sliding relation within an appropriate holevin the baseplate 78. When plunger 25 is down as in Fig. 5, it will be seen thatdepressing rod 77 is positively urged downwardly by plunger 25 to holdauxiliary piston 71 securely in its lowermost position. Depressing rod77 is provided with a snap ring 79 which limits the upward travel of therod 77' when it is drawn up by suction created during ascent of plunger25.

Each time plunger 25 rises during the rapidly successive series of fastreclosing operations, depressing rod 77 is drawn upwardly as in Fig. 6.Normally however, throttle valve 67 and auxiliary piston 71 cannot yieldappreciably from their position in Fig. 5 and whatever yielding mightoccur during the brief interval of plunger ascent will be compensatedwhen the plunger again returns to its lowermost position and strikesdepressing rod 77 so that auxiliary piston 71 is restored to itslowermost position until the latter is fully released intentionally.

Figs. 3 through 6 show an actual embodiment of the invention applied toa circuit interrupter such as that shown in the cited patentapplication. Referring particularly to Fig. 4, it will be observed thatthe selective reclosing mechanism 65 is primarily located beneath amagnetic frame which houses the shunt closing coil 23 and consists inlower magnetic base plate 78 and an upper magnetic member 86 connectedtogether by companion parallel vertical magnetic members 81 one of whichis visible in Fig. 4. The counting or integrating piston 47 is locatedabove and integral with upper magnetic member 80. Extending from the topof integrating piston 47 is an insulating link 82 which performs thedual purpose of driving lockout bar 49 in steps for each opera tion ofthe interrupter and further lifts a link $3 which is connected to anon-metallic selector control rod 84 extending downwardly in parallelismwith the insulating link S2. It will appear shortly hereinafter that theposition of selector control rod 84 determines when in the sequence ofreclosing operations that throttle valve disc 67 will be released forretarding ascent of plunger 25.

Means for breaking the fluid seat of the reservoir 73 and relasingauxiliary piston 71 so that throttle valve 67 may be biased upwardly toclose orifice 66 after any selected reclosing operation will now bediscussed. In the enlarged sectional view of Fig. 5, it will be seenthat the reservoir 73 has a fiuid inlet passageway 85 placing thenormally closed reservoir and the fluid filled space exterior thereto incommunication. During fast reclosing as in Fig. 5, fluid inlet 85 isclosed by means of a control slide valve piston 86 passing transverselyacross inlet 85. Under these circumstances reservoir 73 is sealed andauxiliary piston 71 is prevented from rising upwardly.

In Fig. 6 it will be observed that control slide valve 86 has beenwithdrawn so as to open inlet 85 and allow free admission of fluid intoreservoir 73. Upon this event, biasing spring 69 forces throttle valve67 up by virtue of the fact that auxiliary piston 71 is no longerrestrained by a tendency for a vacuum to be created within thereservoir. Hence, when plunger 25 has begun its ascent as in Fig. 6,depressing rod 77 will be drawn upward until it strikes snap ring 79 andall of the fluid that can enter cylinder 26 under plunger 25 must bedrawn through the small aperture 68 in the center of throttle valve disc67. The maximum retardation of plunger 25 may be established by varyingthesize of aperture 68 in the Original design.

Directly above control slide valve 86 there is a compression returnspring 87 interposed between the top of the slide valve and an annularshoulder 88. By comparing Figs. and 6 it will be seen that spring 87 hasa tendency to restore the slide valve to its lowermost or closedposition whenever vertically upward force is removed therefrom.

Means for establishing the position of the slide valve and accordinglydetermining when the retarded closing operations are to take effect willnow be described. As explained earlier, each time integrating piston 47advances upwardly one step, there is a corresponding upward advance ofselector control rod 84 equal to the distance between adjacent grooves90 in the control stem. A pick-up finger 91 is carried by the controlrod and the finger may be adjusted and fixed in registry with any one ofthe plurality of grooves 90 by withdrawing a straight pin 92, slidingthe finger to alignment with any of the grooves and replacing the pin.Pick-up finger 91 is perforated for embracing slide valve stem 93.Finger 91 is effective to pick up slide valve stem 93 and open slidevalve 86 when the finger abuts a snap ring 94 adjacent the end oft hestem 93. Thus it is seen that there is a lost motion connection betweenthe selector rod 84 and valve stem 93, which lost motion is taken up byupward advancement of integrating piston 47. If it is desired that theinterrupter reclose unretarded through its entire series of operations,the pick-up finger is located in registry with the lowermost of theannular grooves 96 as demonstrated in Fig. 1. If it is desired that theinterruptergo into retarded closing immediately after the first openingoperation thereof, finger fill may be moved as described above to theuppermost of the annular grooves 94) whereupon the first step ofintegrator piston 47 will cause engagement of the pick-up finger 91 withvalve control stem 93 and likewise effect lifting of the slide valve andrelease of vacuum within the fluid reservoir 73. Delayed reclosing timemay be made to take effect at any time during the series of recloseroperations prior to lockout by locating pick-up finger 91 in any one ofthe intermediate annular grooves 90 between the upper and lower limits.

Although the selective reclosing time mechanism constituting theinvention has been described in considerable detail in conenction withan interrupter wherein the reclosing time is governed by the rate ofascent of a plunger, it will be understood that the invention is broadlyapplicable to other hydraulic circuit interrupters involving reversemovement of the plunger.

It will be understood that the invention has little effect if any, uponthe independent timing of the opening operations of theinterrupter. Thisis so because plunger may descend rapidly and unrestrained for reloadingopening spring 1 and closing the main line switches, not shown,regardless of whether the throttle disc valve 67 is in the fastreclosing time position as in Fig. 5, or in the "startled reclosingposition of Fig. 6. This is so because 8 compression spring 69, biasingthrottle valve 67, is relatively soft and offers little impedanceto'discharge of fluid through orifice 66 when plunger 25 is descending.

Use and operation of the selective reclosing time mechanism requires nospecial skill. It merely involves determining whether the particularpower line being protected by the interrupter installation has loadconnected to it which cannot tolerate loss of power even for therelatively short interval normally required for reclosing an interrupterwhile clearing temporary faults. If it is decided that rapid reclosuresare most desirable for what are almost definitely known to be temporaryfaults by reason of experience showing that most faults are cleared uponthe first or second openings of the interrupter, then rapid reclosingafter the first and second openings will be chosen. Hence, when theinterrupter is installed, the customer will set pick-up finger 91 inregistry with one of the intermediate grooves 96 of control rod 84 sothat a lost motion connection will be made with control valve stem 1-3.All subsequent procedure is then automatic.

if a temporary fault occurs which is cleared on the first openingoperations of the interrupter, integrating piston 47 will advanceupwardly, but insutliciently to cause pick-up of valve stem 3 so slidevalve 36 will maintain fluid inlet 85 closed. Under this conditionauxiliary piston 71 cannot rise and throttle valve 67 is ineffective toretard ascent of plunger 25.

If the fault does not clear during the initial opening operations, it ispreferable for well known reasons that the interrupter time delay boththe opening and reclosing operations. Retarded reclosing isautomatically brought into action by the invention when the integratingpiston has stepped suificiently to cause engagement of slide valve stem93 whereupon the slide valve 86 opens for admitting fluid into reservoir73. Thisbreaks the vacuum seal on auxiliary piston 71 and allowsthrottle valve 67 to rise for closing orifice 66, retarding the ascentof plunger 25 and accordingly delaying reclosing time.

If the fault is so permanent that automatic lockout of the interruptertakes place, integrating piston 47 resettles during the lockout period.This permits resettling of slide valve 86 under the influence of itsreturn spring 87 and likewise closing reservoir 73. When the interrupterclosing plunger 25 takes its first power stroke after manual resettingof the interrupter, plunger 25 will drive auxiliary piston 71 back intoreservoir 73 through the agency of depressing rod 77. Depression ofpiston 71 will again cause it to hold throttle valve 67 away fromorifice 66 so that the sequence of fast reclosures followed byretardedreclosures may be repeated if another fault occurs.

Although a preferred embodiment of the invention has been described itis to be construed as suggestive rather than limiting for the inventionmay be variously embodied in a number of currently used interrupterdesigns so its scope is to be interpreted according to theclaims whichfollow.

It is claimed:

1. In a fluid immersed reclosing circuit interrupter ineluding switchmeans, overload responsive means and means actuated. thereby for openingsaid switch means substantially instantaneously, a switch resettingmagnet means including a plunger movable to one position under magneticinfluence for closing said switch means, said I plunger also beingmovable to another position when said switch means opens, means forcounting the number of plunger reciprocations, a cylinder in which saidplunger reciprocates, said cylinder including a fluid orifice foradmitting fluid when the plunger is moving toward said other position,normally inactive throttle valve means controlling said orifice,scelective means operable by. and when said counting means accumulates apredetermined number of counts to render said throttle valve meansactive for restricting the fluid flow only into said cylinder and tothereby determine the rate at which said plunger may move toward itsother position before commencing to reclose said switch means undermagnetic influence.

2. A fluid immersed circuit interrupter including switch means, storedenergy means for opening said switch means instantaneously uponoccurrence of an overload, a switch means closing coil and a cylindersurrounded thereby, a plunger movable to one position in said cylinderfor closing said switch means and loading said stored energy means, saidplunger also being movable to another position when said switch meansopens, a closing switch adapted to energize said closing coil when saidplunger is in its other position and to dc-energize said coil when theplunger is in its one position, means for counting said plungerreciprocations, the aforesaid cylinder including a fluid orifice foradmitting fluid into said cyliinder when said plunger is moving towardits other position, normally inactive throttle valve means controllingsaid orifice, a control valve for rendering said throttle valve meansactive for restricting fluid flow into said cylinder and therebydetermine the rate at which said plunger may move toward its otherposition whereupon said closing switch may re-energize said closingcoil, said control valve being selectively interengaged with saidcounting means and operated thereby when the counting means has executeda predetermined number of counts.

3. In a fluid immersed circuit interrupter characterized by itsincluding switch means and being adapted to execute a plurality of rapidswitch openings and closings and at least one retarded switch closing,the combination with such interrupter of a magnetic plunger movable fromanother position to one position for closing said switch means andreturning to said other position when said switch means open, a cylinderin which said plunger reciprocates, said cylinder including a fluidorifice for admitting fluid when the plunger is moving toward its saidother position, throttle valve means biased toward closing said fluidorifice, a normally closed fluid reservoir, piston means normallyextending from said reservoir into engagement with said biased throttlevalve and restraining the latter from closing said orifice, said pistonbeing held in restraining position by pressure differential exterior andinterior said reservoir, a control valve for opening said reservoir andequalizing the pressure diiferential where upon said orifice may beclosed to restrict fluid flow into said cylinder and retard saidplunger.

4. The invention according to claim 3 wherein said interrupter includesmeans for counting the number of plunger reciprocations, and anadjustable coupling means selectively interconnecting said control valveand counting means, whereby said throttle valve may be operated toeffect retarded movement of said plunger after a preselected number ofcounts.

5. In a fluid immersed circuit interrrupter characterized by itsincluding switch means and being adapted to execute a plurality of rapidswitch openings and closings and at least one retarded switch closing, afluid filled cylinder and a plunger therein movable in one direction toclose said switch means and in another direction when said switch meansopens, said cylinder having a fluid orifice, biased throttle valve meansnormally allowing free ingress and egress of fluid through said orificefor unretarded movement of said plunger, a normally closed fluidreservoir, piston means extending into said reservoir and projectinginto engagement with said throttle valve means, said piston means beingrestrained in said reservoir by normally greater fluid pressure exteriorthereto, a control valve adapted to open said reservoir for equalizingits exterior and interior pressure to thereby allow release of saidpiston means under the bias of said throttle valve means, whereby saidthrottle valve means may close said cylinder orifice for retardingmovement of said plunger when moving in said other direction.

6. The circuit interrupter according to claim 5 including counting meansadvanceable step-by-step in accordance with movements of said plunger, alost motion coupling between said control valve and said counting meansand adapted to actuate said control valve when said counting means hastaken a preselected number of steps.

7. The circuit interrupter according to claim 5 including a countingpiston, hydraulic pump means operable by said plunger to advance saidcounting piston step-by-step upon each operation of the plunger, rodmeans carried by said counting piston for movement therewith, arelatively adjustable lost motion connection between said rod means andcontrol valve effective to actuate said control valve when said countingmeans has taken a preselected number of steps.

8. In a fluid immersed circuit interrupter characterized by itsincluding switch means and being adapted to execute a plurality of rapidswitch openings and closings and at least one retarded switch closing, afluid filled cylinder and a plunger therein movable in one direction toclose said switch means and in another direction when said switch meansopens, said cylinder having a fluid orifice placing the interior andexterior thereof in communication, a throttle valve interposed in thepath of said orifice and normally biased toward closing said orifice,said throttle valve normally permitting free ingress and egress of fluidthrough said orifice in correspondence with reciprocations of saidplunger a normally closed fluid reservoir adjacent said throttle valve,auxiliary piston means extending into said reservoir and projectingnormally into engagement with said throttle valve, said auxiliary pistonhaving a passageway therethrough, a check valve in said passagewaynormally sealing the interior from the exterior of said reservoir andpermitting free descent of said piston, switch operation counting meansincluding a rod advanceable in steps and including groove means spacedapart a distance equal to each step, a pick-up finger selectivelydisposable in registry with said groove means, a control valve havingstem means projecting into lost motion connection with said finger andengageable by the latter after a predetermined number of steps, wherebysaid control valve may be actuated to open said reservoir and allowrelease of said piston means under the bias of said throttle valve.

References Cited in the file of this patent UNITED STATES PATENTS1,648,508 Schweitzer Nov. 8, 1927 2,125,465 Schwager et al. Aug. 2, 19382,769,056 Wallace et al Oct. 30, 1956

